Alan R. Shaffer, principal deputy assistant defense secretary for research and engineering, told a defense industry conference that prototypes and recent tests proved concepts for hypersonic arms, and several systems are part of a high-priority effort by Pentagon weapons developers, despite the era of sharply-diminished defense spending.

Hypersonic vehicles can deliver nuclear or conventional payloads in precision strikes against increasingly hard-to-penetrate air defenses of countries like China, Russia and Iran, he said.

“We, the U.S., do not want to be the second country to understand how to have controlled scramjet hypersonics,” Mr. Shaffer told the Precision Strike Association’s annual review on Tuesday.

The comments come 2 1/2 months after China’s surprise Jan. 9 test of a new hypersonic glide vehicle, dubbed the Wu-14. That ultrahigh speed maneuvering vehicle test represents a major challenge for current U.S. missile defenses, which are designed to counter non-maneuvering ballistic missile threats.